Abstract Nineteen 4-substituted 1, 2, 4-oxadiazol-5-ones (6a-s) were prepared as prodrugs for lipophilic hydroxyguanidines which should be metabolized in vivo to nitric oxide. This hypothesis was tested indirectly by measuring the antithrombotic properties of these compounds 2 h after oral administration to rats (60 mg/kg). In mesenteric arterioles seven compounds moderately (≥ 10%) inhibited the formation of thrombi by a laser beam. ...
